Infrared (IR) imaging systems are often employed to detect objects such as fires, planes, vehicles and people, and to control temperature sensitive industrial processes. A specific type of IR imaging systems, thermal imaging systems, generally operate by detecting the differences in thermal radiance of various objects in a scene and by displaying the differences as a visual image of the scene.
The basic components of a thermal imaging system generally include optics for collecting and focusing IR radiation from a scene, a thermal detector having a plurality of thermal sensors for converting IR radiation to an electrical signal, and electronics for amplifying and processing the electrical signal into a visual display or for storage in an appropriate medium. A chopper may be included in the thermal imaging system to provide a reference signal indicating the amount of background radiation being received by the detector. Choppers may periodically interrupt the transmission of IR radiation to the detector in order to provide this reference signal. For example, the chopper may be a rotating disk with openings that intermittently block incoming IR radiation.
In order to detect and create an image of an object, thermal imaging systems generally rely on infrared radiation that is either emitted by that object or that is reflected off the object. Thermal imaging systems may include a infrared source that emits IR radiation. Such an IR emitter can be used to actively create an image of an object by reflecting IR radiation off of the object and to the thermal detector(s) of the imaging system.